In recent years with the maturity of wireless communication new applications for this technology have emerged. One such example is telephone services provided to commercial aircraft passengers while in flight. A phone system installed aboard an aircraft provides standard telephone services to passengers by transmitting to a ground station which connects to the conventional telephone network. Initially, only one or two phones were placed aboard selected aircraft, but as demand for the service increased, both additional phones and aircraft were included.
The system consists of multiple phone handsets which connect to any one of a number of multiplexors on board the aircraft. Each multiplexor is further connected to radio transceiver to communicate with a ground station, connected to the public swithed telephone network.
Clearly, these airborne phone systems require maintenance and repair like any electromechanical device to insure proper operation. Maintenance and repair are particularly important in the harsh environment in which these systems are installed. Commercial aircraft often make numerous take-offs and landings in a day and the phone systems installed on such aircraft must survive the stress of these take-offs and landings and continue to operate properly. Maintenance is further complicated in that aircraft are only available for programmed maintenance at certain times of the day, and are seldom "overnight" at the same location.
In the past, service technicians were dispatched to perform the maintenance of each radio equipped aircraft. However, forecasting whether a multiplexor or radio transceiver was faulty tended to be inaccurate and was time consuming. Accordingly, each aircraft had to be visited by technicians further complicating scheduling due to the limited availability of aircraft.
It is thus desirable to identify a suspected failed device and dispatch the service technician to repair it rather than examine all the equipment onboard all aircraft.